Cursor start           index 0Ah  CRTC

Layout  b5     COO  Cursor on/off
        b4-b0  CS   Cursor start

- Cursor on/off (bit 5)
        0 : Turn the cursor off.
        1 : Turn the cursor on.

- Cursor start (bits 4-0)
        The number of the scan line within a character box that will
        be the first scan lind displayed for the cursor. Because the
        maximum character size is 32 scan lines, this value may range
        from 0 to 31.